<!DOCTYPE HTML>
<html lang="zh">
<head>
    <meta charset="UTF-8">
    <title>My WebSocket</title>
    <style>
        #message {
            margin-top: 40px;
            border: 1px solid gray;
            padding: 20px;
        }

        .btn {
            height: 30px;
            font-family: 汉仪南宫体简;
            font-weight: bold;
        }
    </style>
</head>
<body>
<label for="nickname" class="btn">Nickname </label><input type="text" id="nickname">
<button onclick="connectWebSocket()" class="btn">Connection</button>
<button onclick="closeWebSocket()" class="btn">Off</button>
<hr/>
<br/>
<label for="text" class="btn">Message：</label><input id="text" type="text"/>
<label for="toUser">Channel: </label><input id="toUser" type="text"/>
<button onclick="send()" class="btn">Send</button>
<div id="message" style="font-family: 微软雅黑"></div>
</body>
<script type="text/javascript">
    var websocket = null;

    function connectWebSocket() {
        //  判断当前浏览器是否支持 WebSocket
        if ('WebSocket' in window) {
            var nickname = document.getElementById("nickname").value;
            if (nickname === "") {
                alert("请输入昵称!");
                return;
            }
            websocket = new WebSocket("ws://localhost:8080/websocket/" + nickname);
        } else {
            alert('Not support websocket')
        }
        //  连接发生错误的回调方法
        websocket.onerror = function () {
            setMessageInnerHTML("error");
        };
        //  连接成功建立的回调方法
        websocket.onopen = function (event) {
            setMessageInnerHTML("【CHAT】: 成功建立连接");
        };
        //  接收到消息的回调方法
        websocket.onmessage = function (event) {
            setMessageInnerHTML(event.data);
        };
        //  连接关闭的回调方法
        websocket.onclose = function () {
            setMessageInnerHTML("【CHAT】: 关闭连接");
        };
        //  监听窗口关闭事件，当窗口关闭时，主动去关闭 websocket 连接，防止连接还没断开就关闭窗口，server端会抛异常。
        window.onbeforeunload = function () {
            websocket.close();
        }
    }

    //  将消息显示在网页上
    function setMessageInnerHTML(innerHTML) {
        document.getElementById('message').innerHTML += innerHTML + '<br/>';
    }

    //  关闭连接
    function closeWebSocket() {
        websocket.close();
    }

    //  发送消息
    function send() {
        var message = document.getElementById('text').value;
        var toUser = document.getElementById('toUser').value;
        var socketMsg = {msg: message, toUser: toUser};

        if (toUser == '') {
            //群聊.
            socketMsg.type = 0;
        } else {
            //单聊.
            socketMsg.type = 1;
        }

        websocket.send(JSON.stringify(socketMsg));
    }
</script>
</html>